Drawbacks in modeling debris flow erosion using the shallow water equations and the finite volume method. Examples from FLATModel and the Rebaixader torrent

FLATModel (Medina et al. 2008) was developed as a modeling tool for debris flow (DF) events. It includes several specific DF features, among them, a simple erosion mechanism was proposed and implemented. The previous validation of this model capability was based on event volume comparison. Now, a more detailed analysis has been performed, and several constraints in its applicability emerge. Model results for erosion present an important dependence on numerical parameters configuration, hence, not only the physical parameters calibration is required. Accuracy in erosion modeling requires proper numeric setup resulting in high computational effort, compromising the model performance. New specific algorithm or erosion computation approach is required.
A part from these numerical aspects, we present some results obtained in the Rebaixader torrent (Central Pyrenees), where a debris-flow monitoring system is installed and annual UAV-surveys are performed.

Medina, V., Hürlimann, M., Bateman, A. (2008) FLATModel: 2D finite volume code for debris-flow modelling. Application to different events occurred in the Northeastern part of the Iberian Peninsula. Landslides, 5, 127-142. https://doi.org/10.1007/s10346-007-0102-3